Question Totally stuck; 2 identical Asus motherboards no won't boot; currently getting A2 error with only OS and 1 other drive connected; help appreciated

[bohemond1099]

Totally stuck; 2 identical Asus motherboards no won't boot; currently getting A2 error with only OS and 1 other drive connected; help appreciated. Both boards are Asus Apex VI X-2999 motherboards; have tried the board with updated bios with 10920X, 7820X, and 7800X; tried with all drives disconnected, with only OS drive connected; have tried 2 PSUs; have tried 1 stick of RAM, have tried board out (but still using same AIO). This whole mess started about 2 weeks ago when the pc shut off on its own; I tore it apart and tried the 10920X and 7800X alternatively, but always got no post AA error, but occasionally the board would boot to windows; got another identical board with 7820X,and never could get to boot on that one; gave me A2 error; put original board back in and same thing now; A2 error on both boards now. I am truly at a loss; when this started the original board was using a 3080Ti from EVGA; afterwards it only occassionally booted with anything BUT the 3080Ti; the 3080Ti works fine with my i7 10700KF system. Am I SOL and toss the boards? Any input would be appreciated.

 

[Lutfij]

but still using same AIO
What AIO are you working with? Might want to see if loosening the screws to the AIO's mounting bracket allows for your system to reagin life.

As for the build, can you please pass on the specs to it like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
Monitor:

 

[bohemond1099]

but still using same AIO
What AIO are you working with? Might want to see if loosening the screws to the AIO's mounting bracket allows for your system to reagin life.

As for the build, can you please pass on the specs to it like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
Monitor:

AIO: EVGA 360 CLC
CPU: i9 10920X on intial mobo; also tried my old i7 7800X and i7 7820X that came with used mobo
Motherboard: Asus Apex VI X299
Ram: 32GB 4x8GB GSkill Trident Z
SSD/HDD: OS Drive M.2. Samsung 970 Evo
1TB M.2.
1.2TB U.2. P3600
1TB Sata SSD
4TB HDD
12TB HDD
DVD RW
GPU: 3080Ti and 1080ti worked fine on initial mobo prior to this; tried GTX 780, R9 Nano, 3080Ti and not working now
PSU: EVGA 1300W Gold initial and EVGA 1000W Gold tried also
Chassis: Corsair 780T
OS: Windows 10 64GB
Monitor: tried HDMI and Displayport monitors

 

[bohemond1099]

Got it sorted; bad original board with electrical issue in tandem with 1 bad 8pin cpu cable. Board would now only post with 8 pin R9 Nano; Any more pins (gtx 780, 980Ti, 3080ti) would not display. New used board worked. I have to quit buying Asus; 3 bad boards on LGA1366/X99/X299 in a 5 year period. Meanwhile my year 2000, 2002, 2006, 2008, 2014, 2017 Gigabyte/Intel/ EVGA boss are still working fine.